1. Chapter 18: Evolution of invertebrate diversity Brief tour animal kingdom diversity - 9 of 35 animal phyla Evolving for perhaps one billion years

2. What is an animal? Multicellular Heterotrophic Eukaryotes Obtain nutrients by ingestion

3. Other distinctive features: No cell wall Extracellular structural proteins Unique intercellular junctions Muscle cells for movement Nerve cells for conducting impulses Life cycles

4. Fig. 18-1b-1 Egg Meiosis 1 Sperm Adult Haploid (n) Diploid (2n) Key

5. Fig. 18-1b-2 Egg Meiosis 1 2 Sperm Zygote (fertilized egg) Haploid (n) Diploid (2n) Key Adult

6. Fig. 18-1b-3 Egg Meiosis 1 3 2 Sperm Zygote (fertilized egg) Eight-cell stage Adult Haploid (n) Diploid (2n) Key

7. Fig. 18-1b-4 Egg Meiosis 1 4 3 2 Sperm Zygote (fertilized egg) Eight-cell stage Adult Blastula (cross section) Haploid (n) Diploid (2n) Key

8. Fig. 18-1b-5 Egg Meiosis 1 5 4 3 2 Sperm Zygote (fertilized egg) Eight-cell stage Adult Blastula (cross section) Early gastrula (cross section) Haploid (n) Diploid (2n) Key

9. Fig. 18-1b-6 Egg Meiosis 1 6 5 4 3 2 Sperm Zygote (fertilized egg) Eight-cell stage Adult Blastula (cross section) Ectoderm Endoderm Internal sac Later gastrula (cross section) Future mesoderm Early gastrula (cross section) Haploid (n) Diploid (2n) Key

10. Fig. 18-1b-7 Egg Meiosis 1 7 6 5 4 3 2 Sperm Zygote (fertilized egg) Eight-cell stage Adult Blastula (cross section) Digestive tract Larva Ectoderm Endoderm Internal sac Later gastrula (cross section) Future mesoderm Early gastrula (cross section) Haploid (n) Diploid (2n) Key

11. Fig. 18-1b-8 Egg Meiosis 1 8 7 6 5 4 3 2 Sperm Zygote (fertilized egg) Eight-cell stage Adult Metamorphosis Blastula (cross section) Digestive tract Larva Ectoderm Endoderm Internal sac Later gastrula (cross section) Future mesoderm Early gastrula (cross section) Haploid (n) Diploid (2n) Key

12. Hox genes Control development Used to investigate phylogenies Provided insights for mechanisms of evolution

13. Origins? Common ancestor 1 billion years ago choanoflagellates

14. Fig. 18-2a 1 2 3 4 5 Colonial protist, an aggregate of identical cells Hollow sphere of unspecial- ized cells Reproductive cells Beginning of cell specialization Infolding Gastrula-like “proto-animal” Somatic cells Digestive cavity Hypothesis for evolution of the first animal… No fossils of this. :(

15. Cambrian Explosion 542 million years ago Dramatic increase in diversity of animal fossils over short period (15 my) Why the sudden increase? Hox genes’ role

16. Most animals are invertebrates 35 or so animal phyla, All but one are invertebrates!

17. Body plans Symmetry Tissue organization Body cavity?

18. Fig. 18-3a Top Bottom Anterior end Dorsal surface Ventral surface Posterior end Symmetry defines ones lifestyle

19. Organization of tissues True tissues = collections of specialized cells that perform specific functions Endoderm Ectoderm Mesoderm

20. Body cavity A fluid filled space between the digestive tract and the outer body wall Cushions internal organs Hydrostatic skeleton

21. Fig. 18-3d Digestive sac (from endoderm) Body covering (from ectoderm) Tissue-filled region (from mesoderm) Flatworm No body cavity

22. Fig. 18-3c Body covering (from ectoderm) Muscle layer (from mesoderm) Digestive tract (from endoderm) Pseudocoelom Round worm Pseudocoelom

23. Fig. 18-3b Coelom Digestive tract (from endoderm) Body covering (from ectoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) Segmented worm True Coelom

24. Protostomes opening becomes the mouth Deuterostomes opening becomes the anus

25. Fig. 18-4 Ancestral colonial protist No true tissues Radial symmetry True tissues Bilateral symmetry Eumetazoans Bilaterians Protostomes Deuterostomes Sponges Cnidarians Echinoderms Chordates Flatworms Molluscs Annelids Arthropods Nematodes

26. Sponges

27. Fig. 18-5d Pores Amoebocyte Skeletal fiber Central cavity Choanocyte in contact with an amoebocyte Flagella Water flow Choanocyte

28. Sponges… Suspension feeders Sessile Simplest of all animals Arose early in animal lineage

29. Fig. 18-4 Ancestral colonial protist No true tissues Radial symmetry True tissues Bilateral symmetry Eumetazoans Bilaterians Protostomes Deuterostomes Sponges Cnidarians Echinoderms Chordates Flatworms Molluscs Annelids Arthropods Nematodes

30. Cnidarians

32. http://bcs.whfreeman.com/thelifewire/content/chp32/32020.html

34. Fig. 18-6d Tentacle Prey “Trigger” Discharge of thread Cnidocyte Coiled thread Capsule (nematocyst)

36. Flatworms Simplest bi-lateral animal 1 mm to 20 m in length! Free-living and parasitic

37. Fig. 18-7a Gastrovascular cavity Mouth Nerve cords Eyespots Nervous tissue clusters Bilateral symmetry

38. Flukes Many have complex life cycles

39. Fig. 18-7b Units with reproductive structures Scolex (anterior end) Hooks Sucker mmmm…. Tape worms!

40. Nematodes Pseudocoelem Three tissue layers Complete diestive tract Cuticle Mouth

41. Free living Live virtually everywhere there is rotting organic matter Live in large numbers Important decomposers Some are predators

42. Caenorhabditis elegans ~ 1000 cells/adults Can trace the lineage of every cell in its body Genome is sequenced

43. Fig. 18-8b

44. Round worms and humans

45. Molluscs

46. Common body plan Foot Visceral mass Mantle

47. Fig. 18-9a Visceral mass Coelom Kidney Mantle cavity Anus Heart Gill Foot Nerve cords Mouth Radula Shell Digestive tract Reproductive organs Radula Digestive tract Mouth

48. Fig. 18-9b Anus Mouth Larva = trocophore

49. Gastropods Bivalves Cephalopods

50. Gastropods Largest group “belly foot” Freshwater, salt water, terrestrial Most have single spiral shell Head with eyes on tips of tentacles

51. Bivalves Shells divided in 2 halves Mostly suspension feeders Mucous coated gills trap food Mostly sedentary

52. Cephalopods “head foot” In most shell is small and internal or missing Beak like jaw and radula Large brains, sophisticated sense organs

53. Annelids Segmented worms 3 main groups: Earthworms and relatives Polychaetes Leeches

54. Fig. 18-10a Anus Segment wall Mucus-secreting organ Brain Dorsal blood vessel Coelom Digestive tract Mouth Pumping segmental vessels Nerve cord Ventral blood vessel Segment wall Excretory organ Nerve cord Bristles Intestine Dorsal blood vessel Longitudinal muscle Ventral blood vessel Bristles Excretory organ Circular muscle Epidermis Segment wall (partition between segments) Giant Australian earthworm

55. Earthworms Hermaphrodites Closed circulatory system Ventral nerve cord Complete digestive tract

56. Polychaetes “many hair” Use chaetae to swim, move, breath Mostly marine Some colonial

57. Leeches Some Bloodsuckers Mostly free-living carnivores Mostly live in freshwater, some marine, few terrestrial Bloodsuckers produce an anesthetic and anti-coagulant

58. Arthropods Most successful animal phylum Segmented Jointed appendages Exoskeleton

59. Fig. 18-11a Cephalothorax Abdomen HeadThorax Antennae (sensory reception) Swimming appendages Pincer (defense) Mouthparts (feeding) Walking legs

60. Open circulatory system Variety of gas exchange organs

61. 4 major lineages Chelicerates Millipedes and Centipedes Crustaceans Insects

62. Chelicerates

63. Fig. 18-11c A scorpion (about 8 cm long) A black widow spider (about 1 cm wide) A dust mite (about 420  m long)

64. Millipedes and Centipedes

65. Crustaceans

66. Insects Segmented body Exoskeleton Jointed appendages Flight Waterproof cuticle Complex life cycle Many with short generations and large # of offspring

67. Complex life cycle Metamorphosis Regal moth

68. Head Thorax Abdomen Antenna Forewing Eye Mouthparts Hindwing Modular Body Plan